Single carrier waveform data transmission and reception based on configurable DFT window

ABSTRACT

In order to maintain flexible system bandwidth and a flexible center frequency, without requiring a cyclic prefix or guard interval, a transmitter apparatus transmits a reference signal based on a single carrier waveform having a mixed symbol structure, in reference signal symbols using at least one of a cyclic prefix and a guard interval and transmits data based on the single carrier waveform without the cyclic prefix or the guard interval. The data may be based on input data processed using overlapping FFT windows, and an amount of overlap between the FFT windows may be configurable by the transmitter or the receiver. An apparatus receiving the downlink transmission comprising data based on a single carrier waveform may process the data based on overlapping FFT windows.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 62/521,138, entitled “Single Carrier Waveform Data Transmission andReception Based on Configurable DFT Window” and filed on Jun. 16, 2017,which is expressly incorporated by reference herein in its entirety.

BACKGROUND Field

The present disclosure relates generally to communication systems, andmore particularly, to a transmission and reception of a single carrierwaveform.

Background

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunication standardis 5G New Radio (NR). 5G NR is part of a continuous mobile broadbandevolution promulgated by Third Generation Partnership Project (3GPP) tomeet new requirements associated with latency, reliability, security,scalability (e.g., with Internet of Things (IoT)), and otherrequirements. Some aspects of 5G NR may be based on the 4G Long TermEvolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunication standards thatemploy these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

Single carrier waveforms such as Discrete FourierTransform-Spread-Frequency-Division-Multiplexing (DFT-s-FDM) or SingleCarrier-Quadrature Amplitude Modulation (SC-QAM) may be used fordownlink transmissions. A single carrier waveform may lack a natural DFTwindow. A cyclic prefix or guard interval may be introduced periodicallyinto the transmitted single carrier waveform signal. The cyclic prefixor guard interval protects the transmission from experiencinginter-symbol interference (ISI) due to timing inaccuracies. The locationof the cyclic prefix or guard interval may define the DFT window for thetransmitter and/or receiver. However, the cyclic prefix or guardinterval may require an added amount of overhead, e.g., that isdiscarded at the receiver.

Aspects presented herein provide the benefits of a single carrierwaveform, e.g., Discrete FourierTransform-Spread-Frequency-Division-Multiplexing (DFT-s-FDM) or SingleCarrier-Quadrature Amplitude Modulation (SC-QAM) while reducing theoverhead required for a periodic cyclic prefix or guard interval. Forexample, the single carrier waveform may be based on a mixed symbolstructure in which a portion of the signal is transmitted with a cyclicprefix or guard interval and another portion of the signal istransmitted without a cyclic prefix or guard interval. For example,single carrier waveform data may be transmitted without a cyclic prefixor guard interval while another part of the signal is transmitted with acyclic prefix or guard interval. For example, reference signals may betransmitted using a cyclic prefix or guard interval. Thus, the referencesymbols may comprise a fixed DFT window, e.g., based on a defined cyclicprefix or guard interval. Without a cyclic prefix or guard interval,there may be no defined DFT window length. Thus, a configurable DFTwindow length may be used for the portion of the signal that istransmitted with the cyclic prefix or guard interval, e.g., the datasignal. The data signal, e.g., may be generated using overlapping FastFourier Transform (FFT) windows based on the configurable DFT window.The transmission of a single carrier waveform having the mixed symbolstructure presented herein may reduce the overhead required by thecyclic prefix or guard interval while maintaining at least some of theflexible system bandwidth and flexible center frequency of the singlecarrier waveform.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided for wireless communication at atransmitter based on a mixed symbol structure. The apparatus transmits areference signal based on a single carrier waveform in reference signalsymbols using at least one of a cyclic prefix and a guard interval. Thereference signal may comprise a fixed Discrete Fourier Transform (DFT)window. The apparatus transmits data based on the single carrierwaveform without the cyclic prefix or the guard interval. The data maycomprise a configurable DFT window. The data may be received based oninput data processed using overlapping Fast Fourier Transform (FFT)windows. A first FFT window may comprise input data comprised in asecond, adjacent FFT window. An amount of overlap between the FFTwindows may be configurable by the receiver or the transmitter.

In another aspect of the disclosure, a method, a computer-readablemedium, and an apparatus are provided for wireless communication at areceiver based on a mixed symbol structure. The apparatus receives areference signal based on the single carrier waveform in referencesignal symbols having at least one of a cyclic prefix and a guardinterval. The reference signal may comprise a fixed DFT window. Theapparatus receives a transmission in symbols comprising data based on asingle carrier waveform without the cyclic prefix or the guard interval.The data may comprise a configurable DFT window. The apparatus thenprocesses the reference signal and data. The apparatus may process thedata based on overlapping FFT windows. A first FFT window may comprisedata comprised in a second, adjacent FFT window. An amount of overlapbetween the FFT windows may be configurable by the receiver or thetransmitter.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a DLframe structure, DL channels within the DL frame structure, an UL framestructure, and UL channels within the UL frame structure, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4A illustrates a mixed symbol single carrier waveform structureincluding a periodic cyclic prefix.

FIG. 4B illustrates a mixed symbol single carrier waveform structureincluding a periodic guard interval.

FIG. 5A illustrates a mixed symbol single carrier waveform structurewithout a periodic cyclic prefix in a data portion.

FIG. 5B illustrates a mixed symbol single carrier waveform structurewithout a periodic guard interval in a data portion.

FIG. 6 illustrates data signal generating using overlapping FFT windows.

FIG. 7 illustrates data signal reception using overlapping FFT windows.

FIG. 8 illustrates an example signal flow of wireless communicationbetween a base station and user equipment.

FIG. 9 is a flowchart of a method of wireless communication.

FIG. 10 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 11 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

FIG. 12 is a flowchart of a method of wireless communication.

FIG. 13 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 14 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, and an Evolved Packet Core (EPC) 160. The basestations 102 may include macro cells (high power cellular base station)and/or small cells (low power cellular base station). The macro cellsinclude base stations. The small cells include femtocells, picocells,and microcells.

The base stations 102 (collectively referred to as Evolved UniversalMobile Telecommunications System (UMTS) Terrestrial Radio Access Network(E-UTRAN)) interface with the EPC 160 through backhaul links 132 (e.g.,S1 interface). In addition to other functions, the base stations 102 mayperform one or more of the following functions: transfer of user data,radio channel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160) with eachother over backhaul links 134 (e.g., X2 interface). The backhaul links134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communication coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacro cells may be known as a heterogeneous network. A heterogeneousnetwork may also include Home Evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communication links 120 between the base stations 102 and theUEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communication links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationlinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100 MHz) bandwidthper carrier allocated in a carrier aggregation of up to a total of YxMHz (x component carriers) used for transmission in each direction. Thecarriers may or may not be adjacent to each other. Allocation ofcarriers may be asymmetric with respect to DL and UL (e.g., more or lesscarriers may be allocated for DL than for UL). The component carriersmay include a primary component carrier and one or more secondarycomponent carriers. A primary component carrier may be referred to as aprimary cell (PCell) and a secondary component carrier may be referredto as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communication link 192. The D2D communication link 192 may use theDL/UL WWAN spectrum. The D2D communication link 192 may use one or moresidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communication may be through a variety of wireless D2Dcommunications systems, such as for example, FlashLinQ, WiMedia,Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunication links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

The gNodeB (gNB) 180 may operate in millimeter wave (mmW) frequenciesand/or near mmW frequencies in communication with the UE 104. When thegNB 180 operates in mmW or near mmW frequencies, the gNB 180 may bereferred to as an mmW base station. Extremely high frequency (EHF) ispart of the RF in the electromagnetic spectrum. EHF has a range of 30GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters.Radio waves in the band may be referred to as a millimeter wave. NearmmW may extend down to a frequency of 3 GHz with a wavelength of 100millimeters. The super high frequency (SHF) band extends between 3 GHzand 30 GHz, also referred to as centimeter wave. Communications usingthe mmW/near mmW radio frequency band has extremely high path loss and ashort range. The mmW base station 180 may utilize beamforming 184 withthe UE 104 to compensate for the extremely high path loss and shortrange.

The EPC 160 may include a Mobility Management Entity (MME) 162, otherMMEs 164, a Serving Gateway 166, a Multimedia Broadcast MulticastService (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC)170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be incommunication with a Home Subscriber Server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the Serving Gateway 166, which itself is connected to the PDNGateway 172. The PDN Gateway 172 provides UE IP address allocation aswell as other functions. The PDN Gateway 172 and the BM-SC 170 areconnected to the IP Services 176. The IP Services 176 may include theInternet, an intranet, an IP Multimedia Subsystem (IMS), a PS StreamingService, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS Bearer Services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSGateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting eMBMS relatedcharging information.

The base station may also be referred to as a gNB, Node B, evolved NodeB (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), or some other suitableterminology. The base station 102 provides an access point to the EPC160 for a UE 104. Examples of UEs 104 include a cellular phone, a smartphone, a session initiation protocol (SIP) phone, a laptop, a personaldigital assistant (PDA), a satellite radio, a global positioning system,a multimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a smart device, a wearabledevice, a vehicle, an electric meter, a gas pump, a toaster, or anyother similar functioning device. Some of the UEs 104 may be referred toas IoT devices (e.g., parking meter, gas pump, toaster, vehicles, etc.).The UE 104 may also be referred to as a station, a mobile station, asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal, a mobile terminal, a wireless terminal, a remoteterminal, a handset, a user agent, a mobile client, a client, or someother suitable terminology.

Referring again to FIG. 1, in certain aspects, the base station 180 maycomprise a mixed symbol signal generation component 199 configured tointroduce a periodic cyclic prefix or guard interval into referencesymbols, wherein the reference signals comprise a fixed DFT window, andto transmit data without a cyclic prefix or guard interval andcomprising a configurable DFT window. The UE 104 may be configured witha mixed symbol signal reception component 198 configured to receive andprocess a received signal having reference signals comprising a fixedDFT window, e.g., based on a cyclic prefix or guard interval and datacomprising a configurable DFT window. For example, the mixed symbolsignal component may process the data signal based on overlapping FFTwindows. The base station and UE may include additional aspects, e.g.,as described in connection with at least FIGS. 2A-14.

FIG. 2A is a diagram 200 illustrating an example of a DL framestructure. FIG. 2B is a diagram 230 illustrating an example of channelswithin the DL frame structure. FIG. 2C is a diagram 250 illustrating anexample of an UL frame structure. FIG. 2D is a diagram 280 illustratingan example of channels within the UL frame structure. Other wirelesscommunication technologies may have a different frame structure and/ordifferent channels. A frame (10 ms) may be divided into 10 equally sizedsubframes. Each subframe may include two consecutive time slots. Aresource grid may be used to represent the two time slots, each timeslot including one or more time concurrent resource blocks (RBs) (alsoreferred to as physical RBs (PRBs)). The resource grid is divided intomultiple resource elements (REs). For a normal cyclic prefix, an RB maycontain 12 consecutive subcarriers in the frequency domain and 7consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) inthe time domain, for a total of 84 REs. For an extended cyclic prefix,an RB may contain 12 consecutive subcarriers in the frequency domain and6 consecutive symbols in the time domain, for a total of 72 REs. Thenumber of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry DL reference (pilot)signals (DL-RS) for channel estimation at the UE. The DL-RS may includecell-specific reference signals (CRS) (also sometimes called common RS),UE-specific reference signals (UE-RS), and channel state informationreference signals (CSI-RS). FIG. 2A illustrates CRS for antenna ports 0,1, 2, and 3 (indicated as R₀, R₁, R₂, and R₃, respectively), UE-RS forantenna port 5 (indicated as R₅), and CSI-RS for antenna port 15(indicated as R).

FIG. 2B illustrates an example of various channels within a DL subframeof a frame. The physical control format indicator channel (PCFICH) iswithin symbol 0 of slot 0, and carries a control format indicator (CFI)that indicates whether the physical downlink control channel (PDCCH)occupies 1, 2, or 3 symbols (FIG. 2B illustrates a PDCCH that occupies 3symbols). The PDCCH carries downlink control information (DCI) withinone or more control channel elements (CCEs), each CCE including nine REgroups (REGs), each REG including four consecutive REs in an OFDMsymbol. A UE may be configured with a UE-specific enhanced PDCCH(ePDCCH) that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs(FIG. 2B shows two RB pairs, each subset including one RB pair). Thephysical hybrid automatic repeat request (ARQ) (HARQ) indicator channel(PHICH) is also within symbol 0 of slot 0 and carries the HARQ indicator(HI) that indicates HARQ acknowledgement (ACK)/negative ACK (HACK)feedback based on the physical uplink shared channel (PUSCH). Theprimary synchronization channel (PSCH) may be within symbol 6 of slot 0within subframes 0 and 5 of a frame. The PSCH carries a primarysynchronization signal (PSS) that is used by a UE 104 to determinesubframe/symbol timing and a physical layer identity. The secondarysynchronization channel (SSCH) may be within symbol 5 of slot 0 withinsubframes 0 and 5 of a frame. The SSCH carries a secondarysynchronization signal (SSS) that is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DL-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSCH and SSCH to form a synchronization signal (SS) block. The MIBprovides a number of RBs in the DL system bandwidth, a PHICHconfiguration, and a system frame number (SFN). The physical downlinkshared channel (PDSCH) carries user data, broadcast system informationnot transmitted through the PBCH such as system information blocks(SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry demodulation referencesignals (DM-RS) for channel estimation at the base station. The UE mayadditionally transmit sounding reference signals (SRS) in the lastsymbol of a subframe. The SRS may have a comb structure, and a UE maytransmit SRS on one of the combs. The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various channels within an UL subframeof a frame. A physical random access channel (PRACH) may be within oneor more subframes within a frame based on the PRACH configuration. ThePRACH may include six consecutive RB pairs within a subframe. The PRACHallows the UE to perform initial system access and achieve ULsynchronization. A physical uplink control channel (PUCCH) may belocated on edges of the UL system bandwidth. The PUCCH carries uplinkcontrol information (UCI), such as scheduling requests, a channelquality indicator (CQI), a precoding matrix indicator (PMI), a rankindicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, andmay additionally be used to carry a buffer status report (BSR), a powerheadroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a packet dataconvergence protocol (PDCP) layer, a radio link control (RLC) layer, anda medium access control (MAC) layer. The controller/processor 375provides RRC layer functionality associated with broadcasting of systeminformation (e.g., MIB, SIBs), RRC connection control (e.g., RRCconnection paging, RRC connection establishment, RRC connectionmodification, and RRC connection release), inter radio access technology(RAT) mobility, and measurement configuration for UE measurementreporting; PDCP layer functionality associated with headercompression/decompression, security (ciphering, deciphering, integrityprotection, integrity verification), and handover support functions; RLClayer functionality associated with the transfer of upper layer packetdata units (PDUs), error correction through ARQ, concatenation,segmentation, and reassembly of RLC service data units (SDUs),re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto transport blocks(TBs), demultiplexing of MAC SDUs from TBs, scheduling informationreporting, error correction through HARQ, priority handling, and logicalchannel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an Inverse FastFourier Transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a Fast Fourier Transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Single carrier waveforms such as DFT-s-FDM or SC-QAM may be used fordownlink transmissions. A single carrier waveform may lack a natural DFTwindow. A cyclic prefix or guard interval may be introducedperiodically. For example, FIG. 4A illustrates a DFT-s-FDM waveform 400having a periodic cyclic prefix between data transmissions. FIG. 4Billustrates an example SC-QAM waveform 401 having a guard intervalperiodically introduced between data transmissions. The location of thecyclic prefix or guard interval naturally defines a DFT window for boththe transmitter and for the receiver. The DFT window of the receiverwill be consistent with that of the receiver. For example, in theDFT-s-FDM waveform 400, a DFT window begins at the end of the cyclicprefix and ends at the beginning of the next cyclic prefix. Similarly,if the SC-QAM waveform 401, a DFT window begins at the end of the guardinterval and ends at the end of the next guard interval following thedata transmission. The cyclic prefix or guard interval serves as a gapbetween adjacent data transmissions providing a cushion to avoidinter-symbol interference (ISI) due to timing inaccuracies. However, theperiodic cyclic prefix or guard interval requires added overhead. Theoverhead required for the cyclic prefix or guard interval may bediscarded at the receiver.

Aspects presented herein provide the benefits of a single carrierwaveform while reducing the overhead required for a periodic cyclicprefix or guard interval. The aspects presented herein enable areduction in overhead while balancing the need to avoid ISI and the needfor a DFT window and maintaining at least some of the flexible systembandwidth and flexible center frequency of the single carrier waveform.For example, the single carrier waveform may transmit a portion of thesignal, e.g., data, without a cyclic prefix or guard interval andanother portion of the signal, e.g., reference signals, with a cyclicprefix or guard interval. FIGS. 5A and 5B illustrate examples of mixedsymbol structures for single carrier waveforms, e.g., waveform 500 andwaveform 501. Waveforms 500, 501 may comprise a cyclic prefix or guardinterval in a portion of the signal, similar to waveforms 400, 401, yetwithout any cyclic prefix or guard interval introduced in the anotherportion of the signal, e.g., data transmission 510, 511. Without acyclic prefix or guard interval in the data transmission 510, 511, theremay be no defined DFT window length for the data. Thus, a configurableDFT window length may be used for the data. This mixed symbol structuremay reduce the overhead required by the cyclic prefix or guard intervalwhile maintaining at least some of the flexible system bandwidth andflexible center frequency of the single carrier waveform.

FIG. 5A illustrates a mixed symbol structure for a single carrierwaveform 500 having reference signal symbols and data symbols. Thesingle carrier waveform 500 may comprise DFT-s-FDM, for example.Reference signal portions 504, 508 of the waveform 500 comprisesreference signal symbols. Portions 502, 506 of the waveform 500 comprisea cyclic prefix inserted with the reference signal portions 504, 508.For example, cyclic prefixes 502, 504 are illustrated surroundingreference signal portion 504. As well, cyclic prefix 506 is illustratedbetween reference signal portions 504 and 508. Data portion 510 of thewaveform 500 comprises data symbols. The data transmission 510 may betransmitted without a cyclic prefix or guard interval introduced in thedata transmission 510. This saves the overhead required for such cyclicprefix/guard interval. The reference signal, e.g., a DMRS signal, of themixed symbol structure may have a cyclic prefix 502, 506 or guardinterval 503, 507 introduced periodically in the reference signalsymbols, e.g., reference signal portion 504, 506. FIG. 5A illustrates anexample with cyclic prefixes 502, 504, introduced in the DMRStransmissions, e.g., reference signal portions 504, 506.

Reference signal portions 505, 509 of the waveform 501 comprisesreference signal symbols. Reference signal portions 503, 507 of thewaveform 501 comprises a guard interval inserted with the referencesignal portions 505, 509. For example, guard intervals 503, 507 areillustrated surrounding reference signal portion 505. As well, guardinterval 507 is illustrated between reference signal portions 505 and509. Data portion 511 of the waveform 501 comprises data symbols. FIG.5B illustrates an example mixed symbol structure for a single carrierwaveform 501 similar to the waveform in FIG. 5A. However, the waveform501 in FIG. 5B comprises guard intervals 503, 505 introducedperiodically into reference signal, e.g., DMRS, transmissions, e.g.,reference signal portions 505, 509. Similar to FIG. 5A, the datatransmission 511 of FIG. 5B is transmitted without a guard interval. Thesingle carrier waveform 501 in FIG. 5B may comprise, e.g., an 11adwaveform such as SC-QAM.

By introducing a cyclic prefix or guard interval in a portion of themixed symbol structure, e.g., the portion comprising the referencesignals, channel estimation can be protected from ISI through the cyclicstructure having gaps between DMRS. By maintaining the quality ofchannel estimation through the use of cyclic prefix or guard intervalsin the reference symbols, frequency domain equalization may be supportedfor the data portion 510, 511. While FIGS. 5A and 5B illustrate thereference signal portion positioned prior to a data portion, thereference signal may also be interlaced with the data portion.

In FIGS. 5A and 5B, the reference symbols comprise a fixed DFT window,e.g., defined by the cyclic prefix or guard interval. The data portion510, 511 does not have a DFT/FFT window that is defined by cyclicprefixes/guard intervals, because the data portion 510, 511 istransmitted without introducing a cyclic prefix or guard interval. Thus,the DFT window, and therefore the FFT window, may be configurable forthe data portion. The transmitter and receiver may use overlapping FFTwindows in order to generate and receive the data signal. Theoverlapping FFT windows provide redundancy that assists the properrecovery of data, even if ISI is present.

FIG. 6 illustrates the use of overlapping FFT windows in the generationof a data signal at a transmitter. The transmitter may be a base station(e.g., base station 180, 310, 804, 1350, the apparatus 1002, 1002′). Abaseline single carrier waveform, e.g., DFT-s-FDM or SC-QAM, may be usedfor the signal, as described in connection with FIGS. 5A and 5B. Thedata may be transmitted without a cyclic prefix or guard interval. Asillustrated, a DFT→tone mapping→Inverse DFT (IDFT) process may be usedto over sample and upconvert the signal to the target subband. Forexample, in a first, DFT process, N₁ time domain samples may beprocessed through a size N₁ DFT, yielding N₁ frequency domain samples.Then, the N₁ frequency domain samples may be padded with (N₂-N₁) zerosand mapped to N₂ tones. The zero-padded N₂ tones may then be processedthrough a size N₂ IDFT, yielding N₂ time domain samples. If thetransmitter directly concatenated data symbols, there may bediscontinuity at the symbol boundary. This was previously solved bywindowing during the cyclic prefix or guard interval portion. Aspresented herein, the data portion can be transmitted without a cyclicprefix or guard interval. FIG. 6 illustrates that overlapping FFTwindows of input data may be used in the DFT process to generate thedata to transmit 602. FIG. 6 illustrates an example of overlapping FFTwindows that include overlapping input data 600 to generate the data fortransmission 602, including portions 604, 606, 608, 610, 612, 614, 616.For example, FFT window 1 includes overlapping input data 600 frompreceding FFT window 0 and from subsequent FFT window 2. FFT window 2includes overlapping input data from preceding FFT window 1 and fromsubsequent FFT window 3. FFT window 3 includes overlapping input datafrom preceding FFT window 2 and from subsequent FFT window 4, and soforth. Thus, the generated data signal for a particular FFT window willinclude overlapping input data also included in adjacent FFT windows.For example, data portion 606 corresponding to FFT window 1 will includeoverlapping data with data portions 604 and 608 corresponding to FFTwindow 0 and FFT window 2. Data portion 608 corresponding to FFT window2 will include overlapping data with data portions 606 and 610corresponding to FFT window 1 and FFT window 3. Data portion 610corresponding to FFT window 3 will include overlapping data with dataportions 608 and 612 corresponding to FFT window 2 and FFT window 4.Data portion 612 corresponding to FFT window 4 will include overlappingdata with data portions 610 and 614 corresponding to FFT window 3 andFFT window 5, and so forth.

The overlapping part of the input data in each of the FFT windows mayexceed the region affected by the boundary effect. The DFT/FFT windowsize and an amount of overlap between FFT windows may be configurable,e.g., by the base station, whereas the cyclic prefix or guard intervalof the reference signal symbols may be preconfigured or fixed. Thus,picocells may use a smaller overlap between FFT windows in generatingthe data signal, because a picocells has a smaller radius and smallertiming inaccuracy than a larger cell that may use a larger overlapbetween FFT windows.

FIG. 7 illustrates the use of overlapping FFT windows in receiving adata signal at a receiver. The receiver may be a UE (e.g., UE 104, 350,802). A baseline single carrier waveform, e.g., DFT-s-FDM or SC-QAM, maybe used for the signal, as described in connection with FIGS. 5A and 5B.The data may be transmitted without a cyclic prefix or guard interval.The data may be generated using overlapping FFT windows, as described inconnection with FIG. 6. Thus, the receiver may perform DFT processing.Without a cyclic prefix or guard interval, the beginning part of eachFFT window may suffer from ISI. In order to reduce the effects of suchISI, the receiver may user overlapping FFT windows to process thereceived data signal.

In FIG. 7, the receiver receives data 700 and uses overlapping FFTwindows of the received data to decode equalized data 702, e.g., decodeddata. The decoded data 702 may correspond, e.g., to input data 600 inFIG. 6. The decoded data 702 may include portions 704, 706, 708, 710,712, 714, 716. The receiver may buffer received data 700 during an FFTwindow and combine processing of adjacent FFT windows to decode thereceived data 700. As illustrated, FFT window 1 includes received dataoverlapping with adjacent FFT window 0 and FFT window 2. FFT window 2includes received data overlapping with adjacent FFT window 1 and FFTwindow 3. FFT window 3 includes received data overlapping with adjacentFFT window 2 and FFT window 4, and so forth. Thus, the UE may processthe received data 700 using the overlapping FFT windows, to decode thereceived data 700. The decoded data 702 may correspond, e.g., to inputdata 600 in FIG. 6.

The size of the FFT windows and the amount of overlap between FFTwindows may be configurable, e.g., by the UE, whereas the cyclic prefixor guard interval of the reference signal symbols may be preconfiguredor fixed. The size of the FFT window and the amount of overlap betweenthe FFT windows used by the receiver may be different than an amount ofoverlap used by the transmitter to generated the data signal. The amountof overlap may be based on an amount of ISI experienced by the UE, andmay be selected to exceed a region affected by the ISI. This mayincrease the number of FFT windows needed for the UE to process the dataduration.

FIG. 8 illustrates a signal flow 800 between a UE 802 (e.g., UE 104,350, 802,) and a base station 804 (e.g., base station 180, 310, 804).The base station 804 may transmit a single carrier waveform based on amixed symbol structure, e.g., DFT-s-FDM, SC-QAM, etc. similar to theexamples in FIGS. 5A, 5B. Although FIG. 8 illustrates a specific examplebetween a base station and a UE, the aspects may be applied for anytransmitter and receiver, e.g., for any transmitter transmitting asingle carrier waveform comprising a reference signal and data.

At 805, the base station generates a DMRS having a periodic cyclicprefix or guard introduced into the reference signal symbols. Forexample, the waveform may comprise aspects similar to at least one ofthe example waveforms described in connection with FIGS. 5A and 5B. Forexample, at least one symbol comprising a cyclic prefix or a guardinterval may be inserted with the generated DMRS. As illustrated inFIGS. 5A and 5B, the cyclic prefix or guard interval may be insertedbefore, after, and/or between DMRS symbols of a waveform.

After generating the DMRS symbols at 805, at 806, the base stationtransmits the reference signal symbols having the periodic cyclic prefixor guard introduced into the reference signal symbols. The transmissionat 806 may comprise a waveform having aspects described in connectionwith the examples of FIGS. 5A and 5B. As described in connection withthe generation of the DMRS at 805, the DMRS transmission may includesymbol(s) having a cyclic prefix or guard interval inserted before,after, and/or between DRMS symbols.

At 807, the UE processes the DMRS based on the fixed DFT window size dueto the cyclic prefix/guard interval. By introducing a cyclic prefix orguard interval in a portion of the mixed symbol structure, e.g., theportion comprising the reference signals, channel estimation at the UEcan be protected from ISI, e.g., through the cyclic structure havinggaps between DMRS. The reference signal may comprise a fixed DFT window.Thus, the receiver may use a fixed FFT window to process the DMRS. FIG.7 illustrates an example use of overlapping FFT windows for a receiverin receiving a data signal. This is merely one example of an algorithmfor processing the reference signal having the cyclic prefix and theguard interval. In other examples, the receiver may use a differentalgorithm to receive the reference signal, e.g., time domain up-samplingand filtering instead of performing FFT.

At 808, the base station generates the data symbols without a cyclicprefix or guard interval. For example, FIGS. 5A and 5B illustrateexamples of data 510, 511 that is generated without a cyclic prefix orguard interval. The base station may generate the data symbols usingoverlapping FFT windows, as illustrated in FIG. 6.

At 810, the base station transmits the generated data symbols without acyclic prefix or guard interval. Thus, the transmission of the singlecarrier waveform may be based on a mixed symbol structure, wherein theDMRS symbols use cyclic prefix or guard interval, but the data symbolsdo not use a cyclic prefix or guard interval. Additionally, thegeneration of the DMRS waveform may use fixed DFT/FFT window, whereasthe generation of DATA waveform may employ a configurable DFT/FFTwindow.

As illustrated At 812, the UE 802 processes the data based on aconfigurable FFT window. For example, the UE may receive the data basedon a configurable FFT window in one example. The UE may process the databased on overlapping FFT windows, as illustrated in FIG. 7. The FFTwindows configured by the base station to generate the data symbols fortransmission may be different than the FFT windows used by the UE toprocess the received data symbols.

FIG. 9 is a flowchart 900 of a method of wireless communication. Themethod may be performed by a transmitter (e.g., the apparatus 1002,1002′) such as a base station (e.g., base station 180, 310, 804)communicating wirelessly with a receiver 1050 (e.g., the apparatus 1302,1302′). The receiver may comprise a UE (e.g., UE 104, 350, 802). Theaspects may be performed by any transmitter. Thus, the method may alsobe performed by a UE, e.g., (e.g., UE 104, 350, 802) that istransmitting, e.g., to a base station (e.g., base station 180, 310,804). While the receiver 1050 is illustrated as a UE in FIG. 9, when thetransmitter is a UE, the receiver 1050 may be a base station. Thewireless communication between the transmitter and receiver may be basedon a mixed symbol structure of a single carrier waveform. The singlecarrier waveform may comprise DFT-s-FDM or an 11ad waveform such asSC-QAM, such as described in connection with FIGS. 5A, 5B.

At 902, the transmitter transmits a reference signal 504, 505, 508, 509based on a single carrier waveform in reference signal symbols using atleast one of a cyclic prefix 502, 506 and a guard interval 503, 507. Thereference signal may comprise a fixed DFT window, e.g., as described inconnection with FIGS. 5A and 5B. The fixed DFT window may be based onthe cyclic prefix or guard interval introduced into the reference signalsymbols. The reference signal may comprise a DMRS, for example.

At 904, the transmitter transmits data based on the single carrierwaveform without a cyclic prefix or a guard interval. The data maycomprise a configurable DFT window, e.g., data 510, 511 as described inconnection with FIGS. 5A, 5B, and 6. The data may be transmitted in datasymbols without a cyclic prefix or a guard interval, e.g., asillustrated in FIGS. 5A and 5B.

The data may be based on input data processed using overlapping FFTwindows, e.g., as described in connection with FIG. 6. For example, afirst FFT window may comprise input data comprised in a second, adjacentFFT window. An amount of overlap between the FFT windows may beconfigurable by the transmitter or by the receiver. Thus, thetransmitter or receiver can choose how much of an overlap is needed.

FIG. 10 is a conceptual data flow diagram 1000 illustrating the dataflow between different means/components in an exemplary apparatus 1002.The apparatus may be transmitter such as a base station (e.g., basestation 180, 310, 804) or a UE (e.g., UE 104, 350, 802). The apparatusincludes a reception component 1004 that receives communication from areceiver 1050. For example, if the apparatus comprise a base station,the reception component may receive uplink communication from a UE and atransmission component 1006 that transmits communication to receiver1050. For example, if the apparatus comprise a base station, thetransmission component may transmit DL communication to a UE. Thecommunication may be transmitted using a mixed symbol structure of asingle carrier waveform, e.g., such as DFT-s-FDM, SC-QAM, etc. Theapparatus may include an RS component 1008 configured to transmit areference signal based on a single carrier waveform in reference signalsymbols using at least one of a cyclic prefix and a guard interval. Thereference signal may comprise a fixed DFT window. The apparatus maycomprise a data component 1010 configured to transmit data based on thesingle carrier waveform without a guard interval or a cyclic prefix. Thedata may comprise a configurable DFT window. The apparatus may include aDFT window component 1012 configured to provide the fixed DFT window forthe reference symbols to reference signal component 1008 and toconfigure and provide the configurable DFT window, or FFT window, to thedata component 1010. The data may be transmitted in data symbols withouta cyclic prefix or a guard interval, while the reference signal symbolsinclude a cyclic prefix or guard interval introduced periodically. Thus,the apparatus may include a CP/GI component configured to introduce thecyclic prefix or guard interval into the reference symbols fortransmission.

The apparatus may include additional components that perform each of theaspects of FIGS. 6 and 7 and blocks of the algorithm in theaforementioned flowcharts of FIGS. 8 and 9. As such, each block in theaforementioned aspects of FIGS. 6 and 7 and the flowcharts of FIGS. 8and 9 may be performed by a component and the apparatus may include oneor more of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

FIG. 11 is a diagram 1100 illustrating an example of a hardwareimplementation for an apparatus 1002′ employing a processing system1114. The processing system 1114 may be implemented with a busarchitecture, represented generally by the bus 1124. The bus 1124 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1114 and the overalldesign constraints. The bus 1124 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1104, the components 1004, 1006, 1008, 1010, 1012,1014, and the computer-readable medium/memory 1106. The bus 1124 mayalso link various other circuits such as timing sources, peripherals,voltage regulators, and power management circuits, which are well knownin the art, and therefore, will not be described any further.

The processing system 1114 may be coupled to a transceiver 1110. Thetransceiver 1110 is coupled to one or more antennas 1120. Thetransceiver 1110 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1110 receives asignal from the one or more antennas 1120, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1114, specifically the reception component 1004. Inaddition, the transceiver 1110 receives information from the processingsystem 1114, specifically the transmission component 1006, and based onthe received information, generates a signal to be applied to the one ormore antennas 1120. The processing system 1114 includes a processor 1104coupled to a computer-readable medium/memory 1106. The processor 1104 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1106. The software, whenexecuted by the processor 1104, causes the processing system 1114 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1106 may also be used forstoring data that is manipulated by the processor 1104 when executingsoftware. The processing system 1114 further includes at least one ofthe components 1004, 1006, 1008, 1010, 1012, 1014. The components may besoftware components running in the processor 1104, resident/stored inthe computer readable medium/memory 1106, one or more hardwarecomponents coupled to the processor 1104, or some combination thereof.The processing system 1114 may be a component of the base station 310and may include the memory 376 and/or at least one of the TX processor316, the RX processor 370, and the controller/processor 375.

In one configuration, the apparatus 1002/1002′ for wirelesscommunication includes means for transmitting a reference signal basedon a single carrier waveform in reference signal symbols using at leastone of a cyclic prefix and a guard interval (e.g., 1006, 1008, 1014),and means for transmitting data based on the single carrier waveformwithout the cyclic prefix or the guard interval (e.g., 1006, 1010,1012). The aforementioned means may be one or more of the aforementionedcomponents of the apparatus 1002 and/or the processing system 1114 ofthe apparatus 1002′ configured to perform the functions recited by theaforementioned means. As described supra, the processing system 1114 mayinclude the TX Processor 316, the RX Processor 370, and thecontroller/processor 375. As such, in one configuration, theaforementioned means may be the TX Processor 316, the RX Processor 370,and the controller/processor 375 configured to perform the functionsrecited by the aforementioned means.

FIG. 12 is a flowchart 1200 of a method of wireless communication. Themethod may be performed by a receiver (e.g., receiver 1050, theapparatus 1302, 1302′). In one example, the receiver may comprise a UE(e.g., UE 104, 350, 802) receiving wireless communication from a basestation (e.g., base station 180, 310, 804). In another example, thereceiver may comprise a base station and the transmitter may comprise aUE.). The single carrier waveform may be based on a mixed symbolstructure. The single carrier waveform may comprise DFT-s-FDM or an 11adwaveform such as SC-QAM, e.g., described in connection with FIGS. 5A,5B.

At 1202, the receiver receives a reference signal based on the singlecarrier waveform in reference signal symbols having at least one of acyclic prefix and a guard interval. The reference signal may comprise afixed DFT window. This is merely one example of an algorithm for thereference signal having the cyclic prefix and the guard interval. Inother examples, the receiver may use a different algorithm to receivethe reference signal, e.g., time domain up-sampling and filteringinstead of performing FFT. The reference signal may comprise a DMRS, andmay be structured as illustrated in FIGS. 5A and 5B, for example.

At 1204, the receiver receives a transmission in data symbols comprisingdata based on the single carrier waveform without a cyclic prefix or aguard interval. The data transmission may comprise a configurable FFTwindow. The single carrier waveform may comprise a signal as describedin connection with FIGS. 5A, 5B, and 6. The data may be received in datasymbols without a cyclic prefix or a guard interval, e.g., as in theexamples illustrated in FIGS. 5A and 5B.

At 1206, the receiver processes the reference signal and the data. Forexample, the reference signal may be processed based on the fixed DFTwindow, whereas the data may be processed based on a configurable FFTwindow. For example, the data may be processed at 1206 based onoverlapping FFT windows, e.g., as described in connection with FIG. 7.For example, a first FFT window may comprise data comprised in a second,adjacent FFT window, as illustrated in FIG. 7. An amount of overlapbetween the FFT windows may be configurable by the receiver or by thetransmitter. The amount of overlap may be based on a level ofinter-symbol interference for the transmission. The amount of overlapbetween the FFT windows configured by the receiver to process thereceived data may be configured independently from a second amount ofoverlap configured by a transmitter.

FIG. 13 is a conceptual data flow diagram 1300 illustrating the dataflow between different means/components in an exemplary apparatus 1302.The apparatus may be a receiver (e.g., receiver 1050). The receiver maycomprise a UE (e.g., UE 104, 350, 802). In another example, the receivermay comprise a base station (e.g., base station 102, 180, 310, 804).While transmitter 1350 is illustrated as a base station, when thereceiver is a base station, the transmitter 1350 may be a UE. Theapparatus includes a reception component 1304 that receivescommunication from a transmitter 1350, and a transmission component 1306that transmits communication to the transmitter 1350. The wirelesscommunication may be based on a mixed symbol structure of a singlecarrier waveform, e.g., DFT-s-FDM, SC-QAM, etc. The reception component1304 may configured to receive a transmission comprising data based on asingle carrier waveform without a guard interval or cyclic prefix. Thedata may comprise a configurable Fast Fourier Transform (FFT) window.The apparatus may include a data component 1310 configured to processingthe data. The data may be processed based on overlapping FFT windows, asdescribed in FIG. 7.

The apparatus may comprise an RS component 1308 configured to receiveand process a reference signal based on the single carrier waveform inreference signal symbols having at least one of a cyclic prefix and aguard interval. The reference signal may comprise a fixed DFT window.The reference signal symbols may include a periodic cyclic prefix orguard interval, whereas the data may be transmitted without a cyclicprefix or guard interval. Thus, the apparatus may include a CP/GIcomponent 1314 that assists the RS component 1308 in processing thereference symbols with introduced cyclic prefix or guard interval. Theapparatus may also include a DFT/FFT window component 1312 thatdetermines a fixed DFT window for the reference symbols and aconfigurable DFT/FFT window for the data.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 8 and12. As such, each block in the aforementioned flowcharts of FIGS. 8 and12 and the aspects illustrated in FIGS. 5A, 5B, 6, and 7 may beperformed by a component and the apparatus may include one or more ofthose components. The components may be one or more hardware componentsspecifically configured to carry out the stated processes/algorithm,implemented by a processor configured to perform the statedprocesses/algorithm, stored within a computer-readable medium forimplementation by a processor, or some combination thereof.

FIG. 14 is a diagram 1400 illustrating an example of a hardwareimplementation for an apparatus 1302′ employing a processing system1414. The processing system 1414 may be implemented with a busarchitecture, represented generally by the bus 1424. The bus 1424 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1414 and the overalldesign constraints. The bus 1424 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1404, the components 1304, 1306, 1308, 1310, 1312,1314, and the computer-readable medium/memory 1406. The bus 1424 mayalso link various other circuits such as timing sources, peripherals,voltage regulators, and power management circuits, which are well knownin the art, and therefore, will not be described any further.

The processing system 1414 may be coupled to a transceiver 1410. Thetransceiver 1410 is coupled to one or more antennas 1420. Thetransceiver 1410 provides a means for communicating with various otherapparatus over a transmission medium. The transceiver 1410 receives asignal from the one or more antennas 1420, extracts information from thereceived signal, and provides the extracted information to theprocessing system 1414, specifically the reception component 1304. Inaddition, the transceiver 1410 receives information from the processingsystem 1414, specifically the transmission component 1306, and based onthe received information, generates a signal to be applied to the one ormore antennas 1420. The processing system 1414 includes a processor 1404coupled to a computer-readable medium/memory 1406. The processor 1404 isresponsible for general processing, including the execution of softwarestored on the computer-readable medium/memory 1406. The software, whenexecuted by the processor 1404, causes the processing system 1414 toperform the various functions described supra for any particularapparatus. The computer-readable medium/memory 1406 may also be used forstoring data that is manipulated by the processor 1404 when executingsoftware. The processing system 1414 further includes at least one ofthe components 1304, 1306, 1308, 1310, 1312, 1314. The components may besoftware components running in the processor 1404, resident/stored inthe computer readable medium/memory 1406, one or more hardwarecomponents coupled to the processor 1404, or some combination thereof.The processing system 1414 may be a component of the UE 350 and mayinclude the memory 360 and/or at least one of the TX processor 368, theRX processor 356, and the controller/processor 359.

In one configuration, the apparatus 1302/1302′ for wirelesscommunication includes means for receiving a downlink transmissioncomprising data based on a single carrier waveform without a cyclicprefix or a guard interval (e.g., 1304, 1310, 1312), means forprocessing the data based on overlapping FFT windows (e.g., 1312, 1310),and means for receiving a reference signal based on the single carrierwaveform in reference signal symbols having at least one of a cyclicprefix and a guard interval (e.g., 1304, 1308, 1314, 1312). Theaforementioned means may be one or more of the aforementioned componentsof the apparatus 1302 and/or the processing system 1414 of the apparatus1302′ configured to perform the functions recited by the aforementionedmeans. As described supra, the processing system 1414 may include the TXProcessor 368, the RX Processor 356, and the controller/processor 359.As such, in one configuration, the aforementioned means may be the TXProcessor 368, the RX Processor 356, and the controller/processor 359configured to perform the functions recited by the aforementioned means.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.

Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of wireless communication at atransmitter based on a mixed symbol structure, comprising: transmittinga reference signal to a receiver based on a single carrier waveform inreference signal symbols using at least one of a cyclic prefix and aguard interval; and transmitting data to the receiver based on thesingle carrier waveform without the cyclic prefix or the guard interval,wherein the data is based on input data processed using overlapping FastFourier Transform (FFT) windows.
 2. The method of claim 1, wherein thedata is transmitted in data symbols without the cyclic prefix or theguard interval.
 3. The method of claim 1, wherein the reference signalcomprises a Demodulation Reference Signal (DMRS).
 4. The method of claim1, wherein the single carrier waveform comprisesDFT-Spread-Frequency-Division-Multiplexing (DFT-s-FDM).
 5. The method ofclaim 1, wherein the single carrier waveform comprises SingleCarrier-Quadrature Amplitude Modulation (SC-QAM).
 6. The method of claim1, wherein a first FFT window comprises the input data comprised in asecond, adjacent FFT window.
 7. The method of claim 1, wherein an amountof overlap between the FFT windows is configurable by the transmitter orthe receiver.
 8. An apparatus for wireless communication at atransmitter based on a mixed symbol structure, comprising: a memory, andat least one processor coupled to the memory and configured to: transmita reference signal to a receiver based on a single carrier waveform inreference signal symbols using at least one of a cyclic prefix and aguard interval; and transmit data to the receiver based on the singlecarrier waveform without the cyclic prefix or the guard interval,wherein the data is based on input data processed using overlapping FastFourier Transform windows.
 9. The apparatus of claim 8, wherein the datais transmitted in data symbols without the cyclic prefix or the guardinterval.
 10. The apparatus of claim 8, wherein the single carrierwaveform comprises DFT-Spread-Frequency-Division-Multiplexing(DFT-s-FDM).
 11. The apparatus of claim 8, wherein the single carrierwaveform comprises Single Carrier-Quadrature Amplitude Modulation(SC-QAM).
 12. The apparatus of claim 8, wherein the reference signalcomprises a Demodulation Reference Signal (DMRS).
 13. The apparatus ofclaim 8, wherein a first FFT window comprises the input data comprisedin a second, adjacent FFT window, and wherein an amount of overlapbetween the FFT windows is configurable by the transmitter or thereceiver.
 14. A method of wireless communication at a receiver based ona mixed symbol structure, comprising: receiving a reference signal basedon a single carrier waveform in reference signal symbols having at leastone of a cyclic prefix and a guard interval; receiving a transmission indata symbols comprising data based on the single carrier waveformwithout the cyclic prefix or the guard interval; and processing thereference signal and the data, wherein the data is processed based onoverlapping Fast Fourier Transform (FFT) windows.
 15. The method ofclaim 14, wherein the reference signal comprises a DemodulationReference Signal (DMRS).
 16. The method of claim 14, wherein a first FFTwindow comprises the data comprised in a second, adjacent FFT window.17. The method of claim 14, wherein an amount of overlap between the FFTwindows is configurable by the receiver or a transmitter.
 18. The methodof claim 17, wherein the amount of overlap is based on a level ofinter-symbol interference for the transmission.
 19. The method of claim17, wherein the amount of overlap between the FFT windows configured bythe receiver to process the received data is configured independentlyfrom a second amount of overlap configured by the transmitter.
 20. Themethod of claim 14, wherein the single carrier waveform comprisesDiscrete Fourier Transform-Spread-Frequency-Division-Multiplexing(DFT-s-FDM).
 21. The method of claim 14, wherein the single carrierwaveform comprises Single Carrier-Quadrature Amplitude Modulation(SC-QAM).
 22. An apparatus for wireless communication at a receiverbased on a mixed symbol structure, comprising: a memory; and at leastone processor coupled to the memory and configured to: receive areference signal based on a single carrier waveform in reference signalsymbols having at least one of a cyclic prefix and a guard interval;receive a transmission in data symbols comprising data based on thesingle carrier waveform without the cyclic prefix or the guard interval;and process the reference signal and the data, wherein the data isprocessed based on overlapping Fast Fourier Transform (FFT) windows. 23.The apparatus of claim 22, wherein a first FFT window comprises the datacomprised in a second, adjacent FFT window.
 24. The apparatus of claim22, wherein an amount of overlap between the FFT windows is configurableby the receiver or a transmitter.
 25. The apparatus of claim 24, whereinthe amount of overlap is based on a level of inter-symbol interferencefor the transmission.
 26. The apparatus of claim 24, wherein the amountof overlap between the FFT windows configured by the receiver to processthe received data is configured independently from a second amount ofoverlap configured by the transmitter.
 27. An apparatus for wirelesscommunication at a transmitter based on a mixed symbol structure,comprising: means for generating data by processing input data usingoverlapping Fast Fourier Transform (FFT) windows; and means fortransmitting a reference signal to a receiver based on a single carrierwaveform in reference signal symbols using at least one of a cyclicprefix and a guard interval, and transmitting the data to the receiverbased on the single carrier waveform without the cyclic prefix or theguard interval.
 28. The apparatus of claim 27, wherein the data istransmitted in data symbols without the cyclic prefix or the guardinterval.
 29. An apparatus for wireless communication at a receiverbased on a mixed symbol structure, comprising: means for receiving areference signal based on a single carrier waveform in reference signalsymbols having at least one of a cyclic prefix and a guard interval, andreceiving a transmission in data symbols comprising data based on thesingle carrier waveform without the cyclic prefix or the guard interval;and means for processing the reference signal and the data, wherein thedata is processed based on overlapping Fast Fourier Transform (FFT)windows.
 30. The apparatus of claim 29, wherein a first FFT windowcomprises the data comprised in a second, adjacent FFT window.
 31. Theapparatus of claim 29, wherein an amount of overlap between the FFTwindows is configurable by the receiver or a transmitter.
 32. Anon-transitory computer readable medium storing code for wirelesscommunication, the code comprising instructions executable by aprocessor to: transmit a reference signal to a receiver based on asingle carrier waveform in reference signal symbols using at least oneof a cyclic prefix and a guard interval; and transmit data to thereceiver based on the single carrier waveform without the cyclic prefixor the guard interval, wherein the data is based on input data processedusing overlapping Fast Fourier Transform (FFT) windows.
 33. Anon-transitory computer readable medium storing code for wirelesscommunication, the code comprising instructions executable by aprocessor to: receive a reference signal based on a single carrierwaveform in reference signal symbols having at least one of a cyclicprefix and a guard interval; receive a transmission in data symbolscomprising data based on the single carrier waveform without the cyclicprefix or the guard interval; and process the reference signal and thedata, wherein the data is processed based on overlapping Fast FourierTransform (FFT) windows.